Thread controlling means for sewing machines



Dec. 24, 1946. F R 2,413,277

THREAD CONTROLLiNG MEANS FOR SEWING MACHINES Filed May 14, 1945 yrederic 7 jea'er Patented Dec. 24, 1946 THREAD CONTROLLING MEANS FOR SEWING MACHINES Frederick F. Zeier, Stratfield, Conn., assignor to The Singer Manufacturing Company, Elizabeth, N. J a corporation of New Jersey Application May 14, 1945,'Serial No. 593,679

16 Claims. 112-255) This invention relates to thread controllin meansfor sewing machines and more particularly to intermittent thread tensions for sewing machines such, for example, as disclosed in United States Patent No. 2,329,681, Sept. 14, 1943.

In sewing canvas, denim and other heavy and/0r hard finish materials, it is essential that a very heavy tension be applied to thethread during the final tightening of the stitch by the thread take-up mechanism, otherwise thread will be stolen from thesupply and the stitch will not be completely set. The tension required at that instant is greater than that required during other portions of the stitch-forming cycle and therefore it has become the practice to provide, in heavy duty machines, a thread tension device, supplementary to the main thread tension, which is rendered effective only at the critical time during the tightening of the stitch.

The primary object of this invention is to provide an improved form of intermittent thread tension device which is easy to assemble and adjust and in which means are provided for varying (a) the degree of tension applied to the thread; (17) the instant in the stitch tightening cycle at which the intermittent tension becomes eifective; and (c) the duration of applied tension.

With the above and other objects in View, as will hereinafter appear. the invention comprises the devices, combinations and arrangements of parts hereinafter set forth and illustrated in the accompanying drawing of a. preferred embodiment of the invention, from which the several features of the invention and the advantages attained thereby will be readily understood by those skilled in the art.

In the drawing,

Fig. 1 is a side elevation of a portion of a sewing machine embodying the present invention.

Fig. 2 is an enlarged horizontal sectional view taken substantially on the line 2-2 of Fig. 1, showing the intermittent tension device in released or ineifective position.

Fig. 3 is a View similar to Fig. 2 but with certain of the parts in elevation and with the intermittent tension device shown in thread engaging position.

Fig. 4 is a sectional view taken substantially on the line 4-4 of Fig. 2 showing, in full and in dotted lines, the time control element of the device in two positions of adjustment.

Fig. 5 is a disassembled perspective view of three of the principal elements of the improved tension device, later to be described.

Referring more specifically to the drawing, the

invention is disclosed as embodied in a sewing machine having a frame including a work-supportl, a bracket-arm 2, terminating in a bracketarm head3 in which is mounted for reciprocation, aneedle-bar 4. At its lower end, the needle-bar carries two eye-pointed needles 5, with which cooperate conventional loop-takers (not shown) in the formation of stitches. The needle-bar is reciprocated from a rotary shaft 6 journaled lengthwise in the arm 2 by mechanism designated generally as T; A needle-thread take-up device (not shown) also is located in the bracket-arm head and isactuated from the arm shaft 6. This takeup device is disclosed in the above noted United State Patent No. 2,329,681, Sept. 14, 1943.

Mounted on the upper portion of the arm 2 are two thre'ad tension devices 8 each of which is adapted to apply a constant tension on one of twoneedle threads 9 which are directed through thread. guides I0 and H to the needle-thread take-up device in the bracket-arm head.

The improved intermittent thread tension, designated generally as I2 in Fig. 1, is located intermediate the constant thread tensions 8 and the thread guide I!) and is actuated by an eccentric l3 secured upon the shaft 6 by set screw Hi. This device comprises a, supporting bushing l5 fitted Within a counterboard aperture l6 provided in the wall of the bracket-arm 2 and is formed with a collar portion l5 and a reduced outwardly extending threaded portion It". The bushing 15 is heldlin the aperture l6 by' a combined clampplate and thread-guide member ll, which, as shown most clearly in Fig. 5, is made of sheet metal and hasv a central aperture ll through which the threaded portion 15 of the bushin passes. The member I1 is provided with perforated ears l8 and laterally off-set bifurcated arms l9. Screws 20, passing through the apertures in the ears l8 and threaded into tapped ho1es-2l in the arm 2, draw the plate i1 into contact wit-hthe outer face of the collar portion W of the bushing and'force the inner face of the collar into contact with the arm 2, thereby holding the .member ll against movement. Slots 22 formed in the arms I9 serve as guides for thethreads 9 passing to and from the intermittent tension.

'Slidingly mounted in a bore 15 in the bushin I5 is a plunger 23, the inner end of which is pivoted, at 24, to a strap 25 which surrounds the eccentric l3. Rotation of the shaft 6, and the eccentric l3 thereon. causes the plunger 23 and parts carried thereby to be reciprocated in the 3 bushing |5 for a purpose hereinafter to be explained.

Threaded upon the portion |5 of the collar l5, outside the member I1, is a stop collar 26 which affords a fixed, but adjustable, abutment for one of two relatively shiftable tension disks, as later will be described. This collar is split circumferentially, as at 21, thus affording relatively yieldable walls 28 and 29. A screw 30, threaded through the wall 28, has its inner end bearing against the wall 29, whereby rotation .of the screw tends to distort one or both of the walls 28 and 29 thus causing the threads in the collar 26 to bind on the threads on the portion |5 of the bushing l5, thereby preventing accidental rotation of the collar on the bushing. Thus the collar 26 may be held in various positions of adjustment on the bushing. Rotatably journaled on the plunger 23, outside the collar 26, is a pair of tension disks 3|, 32 between which pass the needle threads 9.

The plunger 23 is provided with an axial bore 33 into the outer end of which is threaded a plug or abutment block 34. Slidingly mounted in the bore 33 is the head 35 of a rod 35. The outer end portion of the rod passes freely through an aperture in the plug 34 and has threaded thereon an adjusting nut 36 and a lock nut 31.

Fitted upon the rod 35, intermediate the outer end of the plunger 23 and the adjusting nut 36, is a cup-like presser member 38 of which the inner circular edge bears against a washer 39 which, in turn, is adapted to bear against the outer tension disk 32.

A coil spring ii), surrounding the rod 35 in the bore 33, has one end in contact with the rod head 35 and its other end in contact with the fixed abutment block 34. The spring 40 is under compression at all times and therefore tends to draw the rod 35, nut 36 and member 38 inwardly until the base of the member 38 engages the outer en of the plunger 23, as shown in Fig. 2.

As above stated, rotation of the shaft 6, and

the clamping or tensioning period is relatively small.

When the collar 26 is adjusted outwardly on the plunger 23 to the position shown in dotted lines in Fig. 4, the space between the tension disks is reduced. Therefore, upon inward movement of the member 38 and disk 32, the threads are clamped more quickly and remain clamped materially longer than when the collar is in the position shown in full lines. Thus it will be apparent. that this construction affords means for varying the time in the stitch forming cycle at which the intermittent tension becomes effective and also the' length of time during which the tension remains effective.

By adjusting the nut 36 on the rod 35, the

' head may be adjusted toward or from the the eccentric |'3 thereon, effects endwise reciprocation of the plunger 23 and the parts carried thereby. Rotation of the eccentric away from the position shown in Figs. 2 and 4 causes the plunger 23, and the parts'carried thereby, .to be drawn inwardly. Inward movement of the parts shifts the outer tension disk 32 into clamping contact with the thread, or threads, passing be tween the two tension disks; the inner disk 3| being held against inward movement by its contact with the stop collar 26. Inasmuch as the throw of the eccentric I3 is greater than the space between the tension disks, it follows that after inward movement of the outer disk 32, member 38 and rod 35 have been arrested, continued rotation of the eccentric will draw the plunger 23 and plug 34 inwardly away from the base of the member 38, as shown in Fig. 3. This compresses the spring 40 and clamps the threads between the tension disks 3| and 32 thus producing the desired tensioning effect on the threads. A

The time at which the disks 3|, 32 become effective to grip the thread and the duration of the tensioning effect are dependent upon the lost motion between the disk 3| and the movable disk 32.

Thus, with the stop collar 26 adjusted to the position shown in full lines in Fig. 4, the spacebetween the tension disks 3| and 32 is considerable and therefore the gripping of the threads therebetween will be delayed until the eccentric |3 has made the major portion of'its rotation. Likewise with the parts in this position, the duration of abutment block 34, thus varying the compression of the spring 40. It will be understood that the more the spring is compressed the more rigid it will be and therefore the more positive will be the clamping of the threads between the two tension disks. Adjustment of the nut 36 in the opposite direction has the opposite effect. Therefore, this construction also provides means for varying the degree of tension applied to the thread.

It will be apparent that the adjustment which controls the time and duration of the clamping effect is wholly separate from and independent of the adjustment which controls the degree of tension applied to the threads and that, therefore. either adjustment may be made independently of the other.

Having thus set forth the nature of the invention, what I claim herein is:

1. In a sewing machine having a frame; an intermittent thread tension device comprising a bushing carried by said frame, an abutment member mounted on said bushing, a plunger reciprocally supported by said bushing, a pair of opposed tension disks mounted on said plunger, a first one of said disks engaging said abutment member, a yieldable thrust member carried by said plunger and adapted by axial movement of said plunger to force the second of said disks into thread-clamping contact with the firstdisk, and means for reciprocating. said plunger during each stitch-forming cycle.

2. An intermittent thread tension device as set forth in claim 1, including means for varying the time of application of said tension, means for varying the degree of tension applied to the thread, and means for varying the duration of the applied tension.

3. In a sewing machine having a frame provided with an aperture and a rotary shaft journaled in said frame; anintermittent thread tension device comprising a bushing fitted, into the aperture in said frame, and provided With'a reduced extension, a plate surrounding said cxtension and bearing against said bushing to maintain it in said aperture, an abutment member mounted on the reducedextension of said bushing, a plunger reciprocally mounted in said'bushing, a pair of opposed tension disksmounted on said plunger, a first one of said disks engaging said abutment member, a yieldablethrust member carried by said plunger and adapted by axial movement of said plunger to force the second of said disks into thread-clamping contact with the first disk, and means actuated by said shaft for reciprocating said plunger.

4. In a sewing machine having a frame; an intermittent thread tension device comprising a bushing carried by said frame, an abutment member adjustably mounted on said bushing, a plunger reciprocally mounted in said bushing, a pair of opposed tension disks mounted on said plunger, a first one of said disks engaging said abutment member, a yieldable thrust member carried by said plunger and adapted by axial movement of said plunger to force the second of said disks into thread-clamping contact with the first disk, means for adjusting said abutment member on said bushing to vary the time and duration of the thread-clamping action of said disks, and means for reciprocating said plunger.

5. In a sewing machine having a frame provided with an aperture and a rotary shaft journaled in said frame; an intermittent thread tension device comprising a bushing fitted into the aperture in said frame and provided with a reduced extension; a plate surrounding said extension and bearing against said bushing to maintain it in said aperture, said plate being provided with a plurality of perforated ears and a pair of laterally off-set arms affording spaced thread guides, screws passing through said perforated ears and threaded into said frame to secure said plate thereto, an abutment member mounted on the reduced extension of said bushing, a plunger reciprocally mounted in said bushing, a, .pair of opposed tension disks mounted on said plunger, a first one of said disks engaging said abutment member, a yieldable thrust member carried by said plunger and adapted by axial movement of said plunger to force the second of said disks into thread-clamping contact with the first disk, and means actuated by said shaft for reciprocating said plunger.

6. In a sewing machine having a frame and a rotary shaft journaled therein; an intermittent thread tension device comprising a bushing carried by said frame, an abutment collar threaded on said bushing, a plunger reciprocally mounted in said bushing, a pair of opposed tension disks mounted on said plunger, a first one of said disks engaging said abutment collar, a yieldable thrust member carried by said plunger and adapted by axial movement of said plunger to force the second of said disks into thread-clamping contact with the first disk, means for adjusting said collar axially of said bushing to vary the thread-clamping action of said disks; and means actuated by said shaft for reciprocating said plunger.

7. In a sewing machine having a frame and a rotary shaft journaled therein; an intermittent thread tension device comprising a bushing carried by said frame and/having a reduced extension, a split abutment collar mounted on the extension of said bushing, a plunger reciprocally mounted in said bushing, a pair of opposed tension disks mounted on said plunger, a first one of said disks engaging said abutment collar, a yieldable thrust member carried by said plunger and adapted by axial movement of said plunger to force the second of said disks into threadclamping contact with the first disk, means including complemental threads on said bushing and in said collar for adjusting said collar axially of said bushing to vary the thread-clamping action of said disks, means for deflecting one portion of said collar relative to another portion thereof to cause it to bind on the threads of said bushing thereby to maintain said collar in its adjusted position, and means actuated by said shaft for reciprocating said plunger.

8. In a sewing machine having a frame and a rotary shaft journaled therein; an intermittent thread tension device comprising a bushin'g.car riedby said frame, an abutment'member mounted on said bushing, a plunger reciprocally mounted in said bushing and having an axial bore, a plug in the outer end of said bore having a central aperture, inner and outer tension disks mounted on said plunger, the inner disk engaging said abutment member, a rod extending through the aperture in said plug and having a head portion in the bore in said plunger, a coil spring sur-" rounding said rod and having one end bearing on said head and its other end bearing on said plug and urging said rod inwardly, a pressure member surrounding the outer end of said plunger and operatively connected with said rod, and means actuated by said shaft for reciprocating said plunger and the rod therein to cause said pressure member to apply pressure on the outer of said tension disks to force it into threadclamping contact with said inner disk.

9. An intermittent thread tension as set forth in claim 8 in which means is provided for varying the compression of the coil spring in said plunger thereby to vary the pressure capable of being transmitted to said tension disks by said pressure member.

10. In a sewing machine, an intermittently actuated thread tension device operative during each stitch-forming cycle, including a pair of opposed tension disks, means operative periodically for urging said disks together to grip a thread passing therebetween, means for varying the time in the stitch-forming cycle at which tension is applied to the thread, means for varying the degree of tension applied to the thread, and means for varying the duration of the applied tension.

11. A sewing machine intermittent tension device including an outer member, a plunger reciprocally mounted in said outer member, means for reciprocating said plunger during each stitchforming cycle, a pair of thread tension disks mounted on said plunger, and tension varying means carried by said plunger accessible from one end thereof for regulating the degree of tension applied to thread passing between said disks.

12. A sewing machine intermittent tension device including an outer member, a plunger reciprocally mounted in said outer member and having an axial bore, means for reciprocating said plunger during each stitch-forming cycle, a pair of thread tension disks mounted on said plunger, and tension varying means located mainly within said bore and accessible from one end of said plunger for regulating the degree of tension applied to thread passing between said disks.

13. A sewing machine intermittent tension device including a pair of thread-engaging tension disks, means for supporting said disks, means operative periodically for urging said tension disks into thread-engaging relation, and regulatable means effective to vary the time of engagement of said disks with the thread and to vary the duration of the applied tension on the thread.

14. A sewing machine intermittent tension device including a pair of thread tension disks, means for supporting said disks, means operative periodically for urging said tension disks into thread-engaging relation, and regulatable means including a threadedly mounted abutment effective for varying the time of engagement of said disks with the thread and for varying the duration of the applied tension on the thread.

15. An intermittent tension device for sewing machines, comprising, opposed tension-disks supmachines, comprising, opposed tension-disks sup- 10 ported for relative axial movement, an endwise reciprocatory member having a fixed amplitude of reciprocation, means for reciprocating said member, means yieldingly carried by said member for relatively moving said disks into thread-tensioning position, and means for varying the tension application time and the tension duration time.

FREDERICK F. ZEIER. 

